Fiber optic cable has long been known for transmitting signals between ends of the cable, utilizing a signal encoded with light rather than the signal being encoded with an electric current within an electric conductor. For instance, in telecommunications fiber optic cable is often utilized to transmit large volumes of telecommunications data encoded within light passing through the fiber optic cable.
In one particular application for fiber optic cable, an audio or video signal drives an electrical to optical signal converter which generates light and passes it into a fiber optic cable for transmission of the audio or video (or both) signal through the fiber optic cable to a signal processing component at a second location. At the far end of the cable, a light detector is provided which is coupled to an optical to electrical converter so that the signal arrives at the second location.
One such fiber optic cable is referred to by the trademark “TOSLINK,” which features specialized connectors at ends of the cable and at ends of components adapted to be attached to the connectors. A TOSLINK system includes a fiber optic cable usually made from a plastic fiber optic material that connects a DVD player or other component to a receiver or other component. The reason the TOSLINK is used is because it can carry up to five (or more) separate digital signals at once from the DVD player to the receiver. The receiver can separate the signals for delivery to separate speakers out from the receiver. If typical copper wire were utilized for a similar connection, five separate strands of copper wire would typically need to be routed from the DVD player to the receiver.
Other applications for TOSLINK fiber optic cable are being developed in the audio and video field, as well as in home theater applications, automotive applications and in gaming applications. In each of these applications, the TOSLINK fiber optic cable or related cable is located between two separate components. The originating component has an electrical to optical converter which creates the light signal, typically output from an LED. The signal then passes through the fiber optic cable to the second component where a detector is located. The detector receives the signal and appropriately processes the signal for further beneficial use.
A TOSLINK fiber optic cable has two similar connectors on each end. The fiber optic material is typically located within a jacket to protect the fiber optic material between the two connectors. The TOSLINK fiber is plastic normally and is either multi mode or gradient index. The size of the fiber is 1,000 micrometers core size. The cladding, which is also plastic with the TOSLINK fiber, has an outer diameter of 1,100 micrometers.
The fiber optic cable within the TOSLINK system has significant weaknesses. Specifically, the fiber optic cable typically utilized in TOSLINK systems exhibits a signal loss of 160 decibels per meter. Any long cable would lose unacceptable amounts of signal intensity. A second problem with existing TOSLINK fiber optic cable is that it produces “jitter” within the signal. The plastic fiber within the TOSLINK system is very sensitive and when jitter occurs the sound from the speakers which are driven by the signal passing through the fiber is not pure, but distorted. Jitter is believed to be caused by loss of peak amplitude within the digital signal and/or by the elongation of the signal as it travels through the fiber.
Accordingly, a need exists for a fiber optic cable which can work with components designed for a fiber optic signal transmission system, such as the TOSLINK system, but which exhibit less signal degradation so that a higher quality signal can be transmitted, facilitating longer runs of fiber and enhancing a quality of the signal received at the far end of the cable.